Art of multicolor-printing.



' of the original picture or design.

UNITED STATES PATENT OFFICE.

JOSEPH P. KNAPP, OF NEW YORK, N. Y., ASSIGNOR TO AMERICAN LITHOGRAPHIOCOMPANY,

A CORPORATION OF NEW YORK.

ART OF MULTICOLOR-PRINTING.

To all whom it may concern:

Be it known that I, Josnrn P. KNAPP, a citizen of the United States, anda resident of the city of New York, county of New York, and State of NewYork, have invented certain new and useful Improvements in the Art ofMulticolor-Printing, of which the following is a specification.

My invention relates to the art of reproducing multicolor pictures ordesigns and more particularly to that art as carried out byphoto-mechanical methods of printing.

In reproducing a colored picture by photo.- mechanical methods, threeprinting surfaces are preparedfrom photographic images of the originalin such a way that the printing portions of each printing surfacerepresents all of one of three rimary or complementary colors, as red,ye low and blue, which is nec essary, when combined with the properproportions of one or both of the other primary colors, to produce thevarious colors or shades The printing surfaces arethen inked in theirproper colors and impressions are made therefrom in exact register uponsuitable material to pro duce a copy or fac-simile of the original. Theperfection of the reproduction is dependent upon the perfection withwhich the various steps of the process are carried out. The printingportions of the printing surfaces must accurately represent the exactamounts of the various colors which are required in all their varioustones or graduations in every minute portion of the icture or desi n toreproduce the same in a its various co lors and shades; the inks usedmust be of the exact colors and of the exact consistency required; andthe printing must be perfectly executed, not only as regards theregister of the im pressions, but also in regard to the impression ofeach color in all its exact tones and graduations at every part of thedesign. Where it has been attempted to do this threecolor workonmulticolor presses without permitting the ink to dry between theimpressions, much difficulty has been experienced.

: This is chiefly due to the fact that a portion of the paper, which hasbecome more or less saturated with ink by the application of one or moreof the colors of a design, will not receive additional ink, while theink previously applied is still moist, as readily as a portion of thepaper which has not received a charge of ink or on which previouslyapplied ink has Specification of Letters Patent.

Application filed April 9, 1901.

Patented Aug. 25, 1908.

Serial No. 55,083.

become dry. This frequently causes an im perfection in the impression ofa succeeding color wherever it overlies a preceding color or colors, andresults in a false or imperfect coloring or finish of the completedpicture or design. This defect is most noticeable in the darker shadesor tints of the icture. To produce the blacks, for examp e, the threecolors must be printed one on top of the other in exact register and inexactly the required proportions. Where the inks are dried betweenimpressions this can be done with great precision. WVhere the inks arenot allowed to dry between the impressions, however, it is difficult toprint the second and later impressions with the perfection required toproduce the desired results in three-color work.

My invention has for an object to provide a method of multicolorprinting whereby these difficulties may be practically overcome andwhereby excellent multicolor work may be produced on the three-colorprin ciple by means of multicolor presses, or presses in which thesuccessive impressions are madein substantially instantaneous successionand Without drying the ink between impresslons.

WVith these and other objects in view my invention consists as tocertain features in preparingia printing surface for the darkest or mostdefinitive of the color. values or shades of the design, preparing aplurality of printing surfaces for a set of complementary colors, andthen printing upon paper or similar material with the printing surfacesthus prepared without permitting the ink of all the impressions tobecome dry between impressions, the darkest or most definitive of thecolors being preferably printed while the portions of the paper whichreceive that color are. in an unsaturated condition.

The printing plates for the primary colors are preferably prepared byphotographic means, and this may be accomplished by the use of colorscreens in the usual manner. Three of these printing plates arepreferably employed as usual, but obviously two or more may be preparedfor each one of one or more of the primary colors and a series ofimpressions in the same or different shades of the color applied to thepaper Without departing from the principles of my invention. A platesuitable for the darkest or most definitive of the colors may beprepared in any suitable manner, various ways in which this i the inkwhich has been applied to the may be done being within the knowledge ofthose skilled in multicolor printing. This plate is preferably producedfrom the original by photographic means, a color screen being used whichwill bring out the lights and shades in their proper values. It is clearthat it will also be within my invention to use more than one plate forthis color if such practice should be found necessary or desirable.

The darkest color is preferably applied to the paper before any of theother colors are applied in order that a full, strong impression of thatcolor may be obtained at every part of the picture or design. The othercolors are then applied in the usual or any desired order. It will befound that the first color will be strengthened rather than weakened bythe superposition of the other colors and that the imperfections in theimpression of the latter colors resulting from one or more of thedefects of shade impression and register will not appear in the finishedpicture, or will be so slight as not to seriously interfere with thequality of the work. The reason for this will be clear. The points wherethe greatest imperfections in the printing of the complementary colorsexists is where the greatest overlapping of them occurs, andconsequently where the darkest shades are to be produced. The darkshades, however, are produced in a perfect manner by the preliminaryimpression. Where the lighter colors or shades are produced there islittle or no overlapping of the colors and consequently little or noimperfection in the printing.

It is not essential that the darkest color of a set of colors shall be,under all circumstances, the one printed first in point of time. Thus itobviously would be within my invention to print one or more of thelighter tints or colors before the darkest color is printed, but it isreferable that the portion of the paper which is to receive the latterbe not so saturated with ink in a moist or fresh state as to prevent agood impression on the paper.

The particular shade of the dark color is immaterial. It may be a blackor a brown, or any other dark color or shade. It is also immaterial whatparticular set of complementary colors or shades is used.

The essential feature of the invention is that for the purpose ofproducing multicolor printing on the three-color principle in amulticolor press, an additional impression in a fourth color is printedto give depth of shadow and life or brilliancy to the picture; and toproduce the best results, this fourth color should be applied to thepaper while the portions thereof which are to receive that color are inan unsaturated condition. The rapidity with which the colors are appliedis also immaterial so long as there is not enough time allowed betweenimpressions to permit paper to become substantially dry.

It will be seen that the particular mode of procedure by which myinvention, in its broader aspects, may be carried into effect may begreatly varied without departing from the main principles of myinvention and without sacrificing the chief advantages thereof.

' What I claim, and desire to secure by Letters Patent, is:-

1. The improvement in the art of multicolor printing, which consists inpreparing a plurality of printing surfaces for a set of complementarycolors, preparing an additional printing surface for the darkest or mostdefinitive of the color values or shades of the design, and thenprinting upon paper or similar material with the printing surfaces thusprepared in substantial register and Without permitting the ink to drybetween impressions, substantially as described.

2. The improvement in the art of multicolor printin which consists inpreparing a printing surface for the darkest or most y definitive of thecolor values or shades of the design, preparing a plurality of printingsurfaces for a set of complementary colors, and then printing upon paperor similar material with the printing surfaces thus prepared color beingprinted while the portions of the paper which receive that color are inan unsaturated condition, substantially as scribed.

3. The improvement in the art of multicolor printing, which consists inpreparing a printing surface for the darkest or most definitive of thecolor values or shades of the design, preparing by photographic means aplurality of printing surfaces for a set of complementary colors, andthen printing upon paper or similar material with the printing surfacesthus prepared without permitting the ink to dry between impressions, thedarkest or most definitive color being printed while the portions of thepaper which receive that color are in an unsaturated condition,substantially as described.

4. The improvement in the art of multicolor printing, which consists inpreparing by hotographic means three printing surfaces for threecomplementary colors, pre aring an additional printing surface for the carkest or most definitive of the color values or shades withoutpermitting the ink to dry between impressions, the darkest or mostdefinitive.

of the design, and then printing from the I printing surfaces insubstantial register with rinting, which conplurality of printingsurfaces, one for a black or a similar dark or definitive color, and

others for a set of complementary colors, and

then printing from the printing surfaces in substantial register withoutsubstantial dry ing intervals between impressions, the black or similarcolor being printed While the portions of the paper which receive thatcolor are in an unsaturated condition, substan tially as described.

6. The improvement in the art of photo mechanical multicolor printing,Which con sists in preparing by photographic means four printingsurfaces, one for a black or similar dark or definitive color, and threeothers for three complementary colors, and then printing from theprinting surfaces in sub stantial register Without substantial dryingintervals between impressions, the black or similar color being printedbefore the other colors are printed, substantially as described.

7. The improvement in the art of multicolor printing, which consists inpreparing a plurality of printing surfaces for a set of complementarycolors, preparing a printing surface for the darkest or most definitiveof the color values or shades of the design, and making impressions fromthe printing surfaces thus prepared in substantial register theimpressions from the rinting surfaces for the complementary co ors beingmade without permitting the ink to dry between Elie im ressions,substantially as described. a 8. T e improvement in the art of multiolorprinting, which consists in'preparing a plurality of printing surfacesfor a set of comlementary colors re arin a rintin surface for thedarkest or inost defi iiitive 8f the color Values or shades of thedesign, making an impression from the printing surface for thedefinitive color, and then making impressions from the rinting surfacesfor the complementary co ors in substantial register With the firstimpression and Without permitting the ink to dry between theimpressions, substantially as described.

9. The improvement in the art of multicolor printing which consists inmaking impressions in substantial register from a series of platesconstructed to print a set of complementary colors and a dark definitivecolor, the impression from at least one of the plates for printing thecomplementary colors being made Without permitting the ink of a previousimpression to become dry.

10. The improvement in the art of multicolor printing which consists inmaking impressions in substantial register from a series of platesincluding plates constructed to print a set of complementary colors anda plate constructed to print a definitive color, the impression from atleast one of the plates for printing the complementary colors being madewithout permitting the ink of a previous impression to become dry.

In testimony whereof, I have signed my name to this specification, inthe presence of two subscribing witnesses.

JOSEPH P. KNAPP.

Witnesses:

GEO. H. BARNES, JosEPH H. FREEMAN.

